Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
Even though Petey is older, there is a chance that he has a minor digestive disturbance caused by something odd that he may have ingested. The fist thing to do for him is to follow these instructions:
Fast Petey for 12-24 hrs to allow the digestive tract to calm down and heal.
Give him Pepcid AC or Famotidine at 0.5 mg per pound every 8 hrs. That can be purchased over the counter at the pharmacy.
Give only small amounts of water during the fast or ice cubes
After the fast, feed rice and boiled chicken (2/1)
If the vomiting has resolved, then wean Petey back onto regular food. If the vomiting persists especially during the fast, take your Petey to your vet for an exam and lab work to determine the cause for this. This is extremely important since this can cause dehydration or other more serious concerns such as Kidney disease or other metabolic issues, as the last vet mentioned. This is worth a try....it can be very effective if this is minor.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
Sincerely, ***** *****